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CONSTRUCTION TOOL

Roofing Calculator

Estimate sloped roof area and roofing squares from footprint, pitch and number of roof planes.

Roofing Calculator

FREE ONLINE TOOL
Formula and assumptions

Roof area = length × width × √(1 + (rise/12)²) × planes; with waste = area × (1 + waste/100); squares = ft² ÷ 100.

Assumes uniform pitch and rectangular planes. Excludes dormers, hips, valleys, overhangs and flashing. One roofing square is 100 ft². Confirm dimensions and material coverage with a roofer.

10 × 5 m footprint, 6:12 pitch, 2 planes and 10% extra: about 123.0 m² with waste (13.24 roofing squares).

STEP BY STEP

How to use roofing calculator

  1. Check the input units and assumptions.
  2. Review the result and example.

IN PRACTICE

Example

10 × 5 m footprint, 6:12 pitch, 2 planes and 10% extra: about 123.0 m² with waste (13.24 roofing squares).

GOOD TO KNOW

Which formula and assumptions are used?

Assumes uniform pitch and rectangular planes. Excludes dormers, hips, valleys, overhangs and flashing. One roofing square is 100 ft². Confirm dimensions and material coverage with a roofer.

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